A workpiece or other object can be measured for purposes of inspection or design with automated measurement and inspection apparatus, commonly called a co-ordinate measuring machine, or CMM. Such machines generally include a reference table for the workpiece, a movable probe which generates output signals when the probe contacts the workpiece, and a processing system for controlling the probe and calculating and reporting results.
Since most objects can be defined as a combination of familiar shapes and lines, computer systems for measurement and inspection equipment are often programmed with several sub-routines which manipulate the probe to perform basic functions, such as measuring circles, ellipses, lines, planes and other simple geometric figures. These basic sub-routines are then executed in a user selected order to measure a particular workpiece. This is an efficient approach to programming because it allows workpieces of varying shapes and sizes to be measured without creating unique sub-routines for each workpiece.
Measurement and inspection equipment which uses a computer system programmed to perform several basic functions is available from many manufacturers. However, it is customary for each manufacturer to create a unique protocol or syntax for identifying and executing the various basic sub-routines to perform operative functions. Also, in some cases machines made by different manufacturers perform basic operative functions in different ways. The lack of standard syntax for calling basic sub-routines to perform basic functions, and standard approaches to performing those functions, has created problems which the industry has addressed by adopting a standard syntax for identifying and performing these basic functions, called Dimensional Measuring Interface Specification, Version 2.1 ("DMIS"). DMIS was prepared by Computer Aided Manufacturing-International, Inc., Arlington, Tex.
While some manufacturers have adapted their measurement and inspection equipment to be compatible with DMIS, they have done so by providing a translator which converts commands in the standard DMIS syntax into their own unique command syntax. The use of such translators is inefficient because it slows the operation of the equipment, and adds expense because of the added hardware and software needed to accomplish the translation. Thus, there is a need for automated measurement and inspection methods and apparatus which perform basic functions in response to commands in a standard syntax format such as DMIS, without translating the DMIS commands into another format.
CMM's are used to inspect workpieces having a known geometry recorded in an engineering drawing and/or computer aided design (CAD) or computer aided manufacturing (CAM) database. The workpiece can be inspected by taking either the drawing or the database and creating a series of instructions, i.e., a file or part program, for the part. However, such manual programming is tedious and time-consuming, and may need substantial editing and revisions. Thus, there is also a need for automated measurement and inspection methods and apparatus which can create part files for particular workpieces, without manual programming.
Some CMM's are available which automatically generate a part file for a workpiece of unknown dimensions for use in a CAD system, as the operator manually measures the workpiece with the CMM. However, without a standard format or protocol for initiating the various standard subroutines, part files cannot be easily created on one system and later transferred to another because of differences in the interfaces of the machines. The standard syntax used in DMIS allows CAD/CAM systems and CMM's to easily exchange DMIS part files, but existing CMM's require post-processing to translate the DMIS commands into another syntax. Such post-processing requires additional hardware and software, and increases the processing time significantly. Thus, there is also a need for automated measurement and inspection methods and apparatus which create CAD/CAM part files which use DMIS protocol, without such additional translators, compilers or the like.
Accordingly, one object of this invention is to provide new and improved measurement and inspection methods and apparatus.
Another object is to provide new and improved automated, precision measurement and inspection methods and apparatus which perform basic measurement functions in response to commands in a standard syntax format such as DMIS, without translating the DMIS or other standard commands into another format.
Yet another object is to provide new and improved automated measurement and inspection methods and apparatus which create CAD/CAM part files which use DMIS protocol, without translating the DMIS syntax to another protocol.
Still another object is to provide new and improved automated measurement and inspection methods and apparatus which can be operated by remote control, using keypads having designated keys for defining operations which the apparatus performs, and the manner in which the operations are performed.